The Ukrainian crisis has aroused an ugly array of thugs, from the snipers who fired on protesters in Kiev to pro-Russian biker gangs. But numerous multilateral organizations have been implicated too. The crisis began when former Ukrainian President Viktor Yanukovych nixed a trade deal with the European Union in November. Three months later, with Yanukovych in exile and Russia having abruptly seized control of Crimea over the weekend, many more international institutions risk being entangled in the conflict. They range from the Group of Eight (G-8) and United Nations to the Organization for Security and Cooperation in Europe (OSCE). A political settlement will involve a messy mix of these organizations. That may at least be preferable to victory for the thugs.

Any such settlement could also reframe the terms of debate about the international order for years to come. The G-8, which Russia presides over this year, looks like an early institutional casualty. The Western members of the club and Japan—the original G-7—have pulled out of preparatory meetings for a G-8 leaders’ summit planned for Sochi this June. ...